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Journal of Biomechanics

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https://www.readbyqxmd.com/read/28442144/a-proposal-to-evaluate-the-fibers-break-probability-in-ligaments-and-tendons
#1
Marco Bontempi
Understanding the yield and failure mechanisms of ligaments and tendons is important to have a deeper knowledge of their structure and function. Evaluating what are the limits of the human body is also important to prevent injuries in workers, in athletes and the elderly. The tissue yield mechanism was analyzed by modifying and extending a probabilistic model of collagen bundles. Since not usable experimental data are available in the literature, the model and the method were tested using Monte Carlo simulations...
April 13, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433390/a-computational-study-of-invariant-i5-in-a-nearly-incompressible-transversely-isotropic-model-for-white-matter
#2
Yuan Feng, Suhao Qiu, Xiaolong Xia, Songbai Ji, Chung-Hao Lee
The aligned axonal fiber bundles in white matter make it suitable to be modeled as a transversely isotropic material. Recent experimental studies have shown that a minimal form, nearly incompressible transversely isotropic (MITI) material model, is capable of describing mechanical anisotropy of white matter. Here, we used a finite element (FE) computational approach to demonstrate the significance of the fifth invariant (I5) when modeling the anisotropic behavior of white matter in the large-strain regime. We first implemented and validated the MITI model in an FE simulation framework for large deformations...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433389/comparison-of-methodologies-to-assess-muscle-co-contraction-during-gait
#3
H Souissi, R Zory, J Bredin, P Gerus
The aim of this study was to compare co-contraction index (CCI) computed from muscle moments to different co-activation indexes (Co-Act) derived from EMG data at the ankle and the knee joint during gait. An EMG-driven model was used to estimate muscle moments during over-ground walking gait at a self-selected velocity from twelve healthy subjects. The CCI calculated from muscle moments was compared with three Co-Acts estimated from the normalized EMG data. The co-activation methods produced lower values than the CCI during the first double-support and the swing phase at the ankle joint and during the stance phase at the knee joint...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433388/magnetic-resonance-and-diffusion-tensor-imaging-analyses-indicate-heterogeneous-strains-along-human-medial-gastrocnemius-fascicles-caused-by-submaximal-plantar-flexion-activity
#4
Agah Karakuzu, Uluç Pamuk, Cengizhan Ozturk, Burak Acar, Can A Yucesoy
Sarcomere length changes are central to force production and excursion of skeletal muscle. Previous modeling indicates non-uniformity of that if mechanical interaction of muscle with its surrounding muscular and connective tissues is taken into account. Hence, quantifying length changes along the fascicles of activated human muscle in vivo is crucial, but this is lacking due to technical complexities. Combining magnetic resonance imaging deformation analyses and diffusion tensor imaging tractography, the aim was to test the hypothesis that submaximal plantar flexion activity at 15% MVC causes heterogeneous length changes along the fascicles of human medial gastrocnemius (GM) muscle...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433387/how-do-rocker-soled-shoes-influence-the-knee-adduction-moment-in-people-with-knee-osteoarthritis-an-analysis-of-biomechanical-mechanisms
#5
Elizabeth G Madden, Crystal O Kean, Tim V Wrigley, Kim L Bennell, Rana S Hinman
The primary objective was to examine mechanisms behind previously observed changes in the knee adduction moment (KAM) with rocker-soled shoes, in participants sub-grouped according to whether they experienced an immediate decrease, or increase, in peak KAM. In subgroups where frontal plane knee ground reaction force (GRF) lever-arm emerged as a significant predictor, a secondary aim was to examine biomechanical factors that contributed to change in this parameter. Thirty individuals with symptomatic, radiographic knee osteoarthritis (OA) underwent 3D gait analysis in unstable rocker-soled shoes and non-rocker-soled shoes...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28431747/effects-of-vibration-training-in-reducing-risk-of-slip-related-falls-among-young-adults-with-obesity
#6
Feng Yang, Jose Munoz, Long-Zhu Han, Fei Yang
This study examined the effects of controlled whole-body vibration training on reducing risk of slip-related falls in people with obesity. Twenty-three young adults with obesity were randomly assigned into either the vibration or placebo group. The vibration and placebo groups respectively received 6-week vibration and placebo training on a side-alternating vibration platform. Before and after the training, the isometric knee extensors strength capacity was measured for the two groups. Both groups were also exposed to a standardized slip induced by a treadmill during gait prior to and following the training...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433391/mechanisms-of-anterior-posterior-stability-of-the-knee-joint-under-load-bearing
#7
Ryan J Reynolds, Peter S Walker, John Buza
The anterior-posterior (AP) stability of the knee is an important aspect of functional performance. Studies have shown that the stability increases when compressive loads are applied, as indicated by reduced laxity, but the mechanism has not been fully explained. A test rig was designed which applied combinations of AP shear and compressive forces, and measured the AP displacements relative to the neutral position. Five knees were evaluated at compressive loads of 0, 250, 500, and 750N, with the knee at 15° flexion...
April 7, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28427722/biomechanical-investigation-of-post-operative-c5-palsy-due-to-ossification-of-the-posterior-longitudinal-ligament-in-different-types-of-cervical-spinal-alignment
#8
Batbayar Khuyagbaatar, Kyungsoo Kim, Won Man Park, Yoon Hyuk Kim
Post-operative C5palsies are among the most common complications seen after cervical surgery for ossification of the posterior longitudinal ligament (OPLL). Although C5 palsy is a well-known complication of cervical spine surgery, its pathogenesis is poorly understood and depends on many other factors. In this study, a finite element model of the cervical spine and spinal cord-nerve roots complex structures was developed. The changes in stress in the cord and nerve roots, posterior shift of the spinal cord, and displacement and elongation of the nerve roots after laminectomy for cervical OPLL were analyzed for three different cervical sagittal alignments (lordosis, straight, and kyphosis)...
April 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28413069/improving-the-upper-limb-force-feasible-set-evaluation-by-muscles-maximal-isometric-force-identification-and-cocontraction-factors
#9
Vincent Hernandez, Gentiane Venture, Nasser Rezzoug, Philippe Gorce
In order to improve the evaluation of the force feasible set (FFS) of the upper-limb which is of great interest in the biomechanics field, this study proposes two additional techniques. The first one is based on the identification of the maximal isometric force (MIF) of Hill-based muscles models from sEMG and isometric force measurements at the hand. The second one considers muscles cocontraction. The FFS was computed with an upper-limb musculoskeletal model in three different cases. The first one (M1) considered binary muscular activation and a simple MIF scaling method based on the weight and muscle length of the subject...
April 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28410739/changes-in-tendon-spatial-frequency-parameters-with-loading
#10
Stephen J Pearson, Aaron J Engel, Gregory R Bashford
To examine and compare the loading related changes in micro-morphology of the patellar tendon. Fifteen healthy young males (age 19±3yrs, body mass 83±5kg) were utilised in a within subjects matched pairs design. B mode ultrasound images were taken in the sagittal plane of the patellar tendon at rest with the knee at 90° flexion. Repeat images were taken whilst the subjects were carrying out maximal voluntary isometric contractions. Spatial frequency parameters related to the tendon morphology were determined within regions of interest (ROI) from the B mode images at rest and during isometric contractions...
April 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28410738/soft-tissue-artefacts-of-skin-markers-on-the-lower-limb-during-cycling-effects-of-joint-angles-and-pedal-resistance
#11
Jia-Da Li, Tung-Wu Lu, Cheng-Chung Lin, Mei-Ying Kuo, Horng-Chaung Hsu, Wu-Chung Shen
Soft tissue artefacts (STA) are a major error source in skin marker-based measurement of human movement, and are difficult to eliminate non-invasively. The current study quantified in vivo the STA of skin markers on the thigh and shank during cycling, and studied the effects of knee angles and pedal resistance by using integrated 3D fluoroscopy and stereophotogrammetry. Fifteen young healthy adults performed stationary cycling with and without pedal resistance, while the marker data were measured using a motion capture system, and the motions of the femur and tibia/fibula were recorded using a bi-plane fluoroscopy-to-CT registration method...
April 3, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28395878/cerebral-aneurysm-blood-flow-simulations-are-sensitive-to-basic-solver-settings
#12
Kendall D Dennis, David F Kallmes, Dan Dragomir-Daescu
Computational modeling of peri-aneurysmal hemodynamics is typically carried out with commercial software without knowledge of the sensitivity of the model to variation in input values. For three aneurysm models, we carried out a formal sensitivity analysis and optimization strategy focused on variation in timestep duration and model residual error values and their impact on hemodynamic outputs. We examined the solution sensitivity to timestep sizes of 10(-3)s, 10(-4)s, and 10(-5)s while using model residual error values of 10(-4), 10(-5), and 10(-6) using ANSYS Fluent to observe compounding errors and to optimize solver settings for computational efficiency while preserving solution accuracy...
April 3, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28431748/a-benchtop-biorobotic-platform-for-in-vitro-observation-of-muscle-tendon-dynamics-with-parallel-mechanical-assistance-from-an-elastic-exoskeleton
#13
Benjamin D Robertson, Siddarth Vadakkeveedu, Gregory S Sawicki
We present a novel biorobotic framework comprised of a biological muscle-tendon unit (MTU) mechanically coupled to a feedback controlled robotic environment simulation that mimics in vivo inertial/gravitational loading and mechanical assistance from a parallel elastic exoskeleton. Using this system, we applied select combinations of biological muscle activation (modulated with rate-coded direct neural stimulation) and parallel elastic assistance (applied via closed-loop mechanical environment simulation) hypothesized to mimic human behavior based on previously published modeling studies...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28411958/effects-of-step-length-and-step-frequency-on-lower-limb-muscle-function-in-human-gait
#14
Yoong Ping Lim, Yi-Chung Lin, Marcus G Pandy
The aim of this study was to quantify the effects of step length and step frequency on lower-limb muscle function in walking. Three-dimensional gait data were used in conjunction with musculoskeletal modeling techniques to evaluate muscle function over a range of walking speeds using prescribed combinations of step length and step frequency. The body was modeled as a 10-segment, 21-degree-of-freedom skeleton actuated by 54 muscle-tendon units. Lower-limb muscle forces were calculated using inverse dynamics and static optimization...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28385335/foot-structure-is-correlated-with-performance-in-a-single-joint-jumping-task
#15
Herman van Werkhoven, Stephen J Piazza
Variability in musculoskeletal structure has the potential to influence locomotor function. It has been shown, for example, that sprinters have smaller Achilles tendon moment arms and longer toes than non-sprinters, and toe length has been found to correlate with toe flexor work in running humans. These findings suggest that interindividual variation in human foot structure allows for function that is adapted to various motor tasks. The purpose of this study was to test for correlations between foot anthropometry and single-joint maximal-height jumping performance...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28366438/measuring-joint-kinematics-of-treadmill-walking-and-running-comparison-between-an-inertial-sensor-based-system-and-a-camera-based-system
#16
Corina Nüesch, Elena Roos, Geert Pagenstert, Annegret Mündermann
Inertial sensor systems are becoming increasingly popular for gait analysis because their use is simple and time efficient. This study aimed to compare joint kinematics measured by the inertial sensor system RehaGait® with those of an optoelectronic system (Vicon®) for treadmill walking and running. Additionally, the test re-test repeatability of kinematic waveforms and discrete parameters for the RehaGait® was investigated. Twenty healthy runners participated in this study. Inertial sensors and reflective markers (PlugIn Gait) were attached according to respective guidelines...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28365064/subject-specific-2d-3d-image-registration-and-kinematics-driven-musculoskeletal-model-of-the-spine
#17
A H Eskandari, N Arjmand, A Shirazi-Adl, F Farahmand
An essential input to the musculoskeletal (MS) trunk models that estimate muscle and spine forces is kinematics of the thorax, pelvis, and lumbar vertebrae. While thorax and pelvis kinematics are usually measured via skin motion capture devices (with inherent errors on the proper identification of the underlying bony landmarks and the relative skin-sensor-bone movements), those of the intervening lumbar vertebrae are commonly approximated at fixed proportions based on the thorax-pelvis kinematics. This study proposes an image-based kinematics measurement approach to drive subject-specific (musculature, geometry, mass, and center of masses) MS models...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28363382/the-biomechanical-consequences-of-longirostry-in-crocodilians-and-odontocetes
#18
M R McCurry, C W Walmsley, E M G Fitzgerald, C R McHenry
Unrelated clades of aquatic tetrapod have evolved a similar range of skull shapes, varying from longirostrine (elongate and narrow rostrum) to brevirostrine (short rostrum). However, it is unclear which aspects of organismal performance are associated with this convergence in the range of skull shapes. Furthermore, it is not known how fundamental anatomical differences between groups influence these relationships. Here we address this by examining the load bearing capabilities of the skulls of two of the most diverse groups of living aquatic tetrapod: crocodilians and odontocetes...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28372795/a-four-dimensional-computed-tomography-comparison-of-healthy-and-asthmatic-human-lungs
#19
Nariman Jahani, Sanghun Choi, Jiwoong Choi, Babak Haghighi, Eric A Hoffman, Alejandro P Comellas, Joel N Kline, Ching-Long Lin
The purpose of this study was to explore new insights in non-linearity, hysteresis and ventilation heterogeneity of asthmatic human lungs using four-dimensional computed tomography (4D-CT) image data acquired during tidal breathing. Volumetric image data were acquired for 5 non-severe and one severe asthmatic volunteers. Besides 4D-CT image data, function residual capacity and total lung capacity image data during breath-hold were acquired for comparison with dynamic scans. Quantitative results were compared with the previously reported analysis of five healthy human lungs...
March 18, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28365063/mechanical-response-and-deformation-mechanics-of-type-iv-pili-investigated-using-steered-coarse-grained-molecular-dynamics-simulation
#20
Xiaoxi Zhao, Yankai Liu, Zhouhang Guo, Yizhe Zhang, Yongchi Li, Wei Liu
Type IV pili are long filamentous structures on the surface of bacteria, which can be rapidly assembled or disassembled with pilin subunits by molecular motors. They can generate force during retraction and are involved in many bacterial functions. Steered molecular dynamics simulations with coarse-grained MARTINI models are carried out to investigate the mechanical behaviors of pili under tension. Our study is the first to report a Young's modulus of 0.80±0.07GPa and a spring constant of 1294.6±116.5kJmol(-1)nm(-2) for pilus...
March 18, 2017: Journal of Biomechanics
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